Scientists found weeds-killing fungus

Homeowners stripped of chemical weed control products to fight dandelions and thistles may soon have a new ally.

After decades of search, Agriculture Canada scientists have isolated a fungus that attacks dandelions and other weeds but leaves grass alone.

The fungus, phoma macrostoma, could be on the market in two years, said Karen Bailey, the lead researcher on the project in Saskatoon.

"The initial application is for homeowner use,” said Bailey.

Londoners and other Ontarians are banned from using chemical pesticides under a law that took effect April 22, 2009.

The search for a fungus to combat weeds started in the 1980s when researchers from across Canada began collecting samples of sick Canada thistle plants for scientists in Saskatoon.

The scientists noticed phoma macrostoma was recurring in some samples.

"Basically, what it will do is turn the plants white that will be affected by it. When those plants are white, they can’t photosynthesize and they eventually use up their root storage and then they die,” said Bailey.

The fungus is applied to the soil in a granular form and can be spread before or after dandelions and thistles emerge. It has also been found to attack clover, chickweed and ragweed.

It works against the weeds by producing a toxin in the soil that attacks the roots of the plants.

The fungus has received Health Canada approval for use in turf grass and has been licensed to garden and lawn care giant Scotts to bring it to market. How much it will cost homeowners will be up to Scotts, said Bailey,

"I think it will be affordable, but I don’t think it will be what I would call cheap initially,” she said. “It certainly won’t be as cheap as old conventional materials.”

The challenge now is to find a way of scaling up production of the fungus from the research lab to commercial production.

"I think in two years you will see it on the shelf,” Bailey said.

Bailey said the fungus doesn’t persist in the soil.

"We can see that it tends to increase up to about two months and then it starts to decline. After four months it starts to get very faint and a year later we can’t detect it at all in the soil,” she said.
Research is underway to see if the fungus can be used for weed control in wheat and barley crops.